This invention relates to utility cover extensions and more particularly to utility cover extensions for adjusting the level of a utility cover to a new grade.
In the repair and resurfacing of streets and highways, it is frequently found that the repaired or resurfaced roadway is substantially higher than the original roadway. Accordingly, the top surface of the utility covers in the roadway, such as manhole covers, water and gas valve covers, gas and water meter covers and the like, are disposed substantially below the new road surface. This lower position of the utility cover creates a hazardous driving condition. These utility covers must be raised in order to adjust their top surfaces to that of the new level of the roadway.
In the original roadway, the utility cover is positioned over an access opening of a utility housing. The access opening generally has a support flange on which the utility cover is supported with the top surface of the utility cover to the level as the original highway.
One known construction for raising a utility cover to the new grade of the repaired or resurfaced roadway are manhole cover supports used to raise a manhole cover above the manhole housing so that the top of the manhole cover is at the new grade of the roadway. These manhole cover supports are designed to fit into the manhole housing and support the cover so that its top surface is at the new level of the roadway. The use of such manhole cover supports are desirable since it becomes unnecessary to replace the frame which is embedded in a paved road.
When raising the utility cover to a new grade, it is desirable to provide a utility cover support which when assembled with the utility frame and cover resists displacement or dislocation of those components under normal service conditions of the roadway. Under such service conditions various vehicle traffic loadings occur including axle, wheel and impact loadings, and various temperature conditions, such as steam from steam lines, and various chemical conditions, for example, spills of oil or gasoline on the roadway, also occur. If such service conditions create displacement or dislocation of the utility cover extension, utility housing, or cover, a depression or protrusion in the road surface will be realized which creates a driving hazard.
Furthermore, other hazardous driving conditions may be created, for example, when a impact loading is made on one of the components, such as the cover, and the cover pops out of the opening. Accordingly, it is desirable that relative movement between the components be resisted under such service conditions which includes the ability to absorb impact loadings, operate under various temperature conditions and various chemical environments.
It is also desirable to provide a utility cover support which resists rotation of the utility cover which results in wear between the components. For example, after repeatedly impacting the utility cover on one side, the cover tends to rotate thus abrading the surfaces between the cover and the utility support. Such wear creates a looser fit and allows more movement between the cover and the cover support. As the surfaces between the utility cover and utility cover support wear, the likelihood of displacement or dislocation of the cover under normal service conditions is increased which accordingly creates a hazardous driving condition.
It is also desirable to minimize the flow of surface water and other contaminants into the access opening of the utility housing. Water infiltration into the access opening of the utility housing has been a continuous problem with telephone companies, municipal public work departments and other public utility companies. For example, it is desirable to segregate different types of municipal water systems. Large volumes of additional waste water must be treated when surface water infiltrates into a sewer system through a manhole. The overloading of sewage systems has increased in importance from many years ago and the key factor is that today there is significantly less pervious area than there was years ago. This factor is due to larger impervious street surfaces that collect more drainage water as well as smaller building lot sizes which cut down on the amount of overall pervious area. By significantly decreasing the flow of storm and drainage water into the access opening, existing water treatment facilities can handle more sewage capacity.
In the case of electric and gas underground systems, in many instances, continuous pumping of water is required before utility men can enter a manhole because of water infiltration between the manhole cover components. In the case of utility cover assemblies for utility valves, meters and the like, the surface water and other contaminants such as dirt, deteriorate the valve or meter and inhibit its operation and ease of access thereto. It is also desirable to keep contaminants out of the utility frame in the case of gas and water meters to allow for ready access to the gas and water meters and reading thereof and their operation.
It is desirable to provide a utility cover support which reduces noise generated under normal service conditions. It is also desirable to absorb and dissipate the energy exerted on the components of the utility cover support assembly under normal service conditions.